Definition of Precipitation Reaction

Definition of Precipitation Reaction A precipitation reaction is a  type of chemical reaction in which two soluble salts in aqueous solution combine and one of the products is an insoluble salt called a  precipitate. The precipitate may stay in the solution as a suspension, fall out of solution on its own, or can be separated from the liquid using centrifugation, decantation, or filtration. The liquid that remains when a precipitate forms is called the supernate. Whether or not a precipitation reaction will occur when two solutions are mixed may be predicted by consulting a solubility table  or the solubility rules. Alkali metal salts and those containing ammonium cations are soluble. Acetates, perchlorates, and nitrates are soluble. Chlorides, bromides, and iodides are soluble. Most other salts are insoluble, with exceptions (e.g., calcium, strontium, barium sulfides, sulfates, and hydroxides are soluble). Note that not all ionic compounds react to form precipitates. Also, a precipitate may form under certain conditions, but not others. For example, changes in temperature and pH can affect whether or not a precipitation reaction will occur. Generally, increasing temperature of a solution increases the solubility of the ionic compounds, improving the likelihood of precipitate formation. The concentration of the reactants is also an important factor. Precipitation reactions are usually single replacement reactions or double replacement reactions. In a double replacement reaction, both ionic reactants dissociate in water and their ions bonds with the respective cation or anion from the other reactant (switch partners). In order for a double replacement reaction to be a precipitation reaction, one of the resulting products must be insoluble in aqueous solution. In a single replacement reaction, an ionic compound dissociates and either its cation or anion bonds with another ion in solution to form an insoluble product. Uses of Precipitation Reactions Whether or not mixing two solutions produces a precipitate is a useful indicator of the identity of the ions in an unknown solution. Precipitation reactions are also useful when preparing and isolating a compound. Precipitation Reaction Examples The reaction between silver nitrate and potassium chloride is a precipitation reaction because solid silver chloride is formed as a product.AgNO3(aq) KCl(aq) → AgCl(s) KNO3(aq) The reaction may be recognized as a precipitation because two ionic aqueous solutions (aq) react to yield a solid product (s). Its common to write precipitation reactions in terms of the ions in the solution. This is called a complete ionic equation: Ag  (aq)   NO3−(aq)   K  (aq)   Cl−(aq)  Ã¢â€ â€™ AgCl  (s)   K  (aq)   NO3−(aq) Another way to write a precipitation reaction is as a net ionic equation. In the net ionic equation, the ions that dont participate in the precipitation are omitted. These ions are called spectator ions because they seem to sit back and watch the reaction without taking part  in it. In this example, the net ionic equation is: Ag(aq)   Cl−(aq)  Ã¢â€ â€™ AgCl  (s) Properties of Precipitates Precipitates are crystalline ionic solids. Depending on the species involved in the reaction, they may be colorless or colorful. Colored precipitates most often appear if they involve transition metals, including the rare earth elements.

Stem Cell Reserch English 1301 Profe Essay

Stem Cell Reserch English 1301 Profe Essay Stem Cell Reserch English 1301 Profe Essay Trosey Egbujor Professor Tete English 1301 October 31, 2014 Embryonic Stem Cell Research Embryonic stem cell research dose it saves lives? Or killing new life? Some say it is murder, others say it is not because the embryo is not a living human being until it reaches eight weeks of fertilization. Is it immoral to allow the further destruction of embryos to be used to save one life yet kill another? Embryonic stem cell research is when scientists suck the entire stem cell from the embryo, terminating and using the stem cell it, to help fight disease like Bone- marrow disease, Parkinson’s and sickle-cell anemia although these disease have had great benefited from the stem cell research one can get the same results from blood found in the umbilical cord and placenta or even bone marrow. It’s immoral to use a living being when other means of research are available and has proven to be useful in the search for a cure in these diseases. Embryonic stem cell research should not be legal because the embryo is a living human being. There is life in the embryo from the time sperm and egg meet. Life is sacred at all stages of development. 60th human stem cell has been made these sixth embryos which held great promise that could lead to breakthrough therapies and cures. Former president George Bush gave federal money to support research on those lines and funded research on adult stem cells, such as bone marrow, fetal blood cells taken from umbilical cords and other adult stem cells found in skin, muscle and the intestine, and then all would be well. (Lui) stated â€Å"Human embryonic stem cell is often described as master cells able to develop into any other type of cell in the human body† (Lui 2). â€Å"Potential sources for human embryonic stem cell include embryo created via in vitro fertilization for either research or reproduction five to nine weeks old embryo or fetuses obtained through elective abortion and embryo created through cloning or somatic cell nuclear transfer† (2).â€Å"Stem cell which are derived from adult tissues such as umbilical cord blood or bone marrow are distinct from embryonic stem cell and do not naturally exhibit the same developmental characteristics or behaviors†(2). In 2007, researchers in Japan and the United States published report that they had successfully induced human somatic cells to exhibit pluripotent characteristics. This advancement notwithstanding many stem cell researchers continue to argue that embryonic stem cell procurement is necessary in order to provide among others things the gold standard against which other means of pluripotent stem cell procurement are measured†( 2,3)â€Å"In January of 1999 the General Counselor of Health and Human Services concluded that the Dickey Amendment’s prohibitions against the use of (HHS) appropriated funds for human embryo research would not apply to research using stem cells because such cells are not a human embryo within the statutory definition so (HHS) concluded that (NIH) could not fund research that used stem cells derived from the embryo† (4). Researchers discovered that using cells found in bone marrow, and umbilical cords from the birth of a child proved to work ju st as well in providing cures for Parkinson’s and sickle-cell anemia disease would not destroying human embryos. When George Bush was in office as President of the United States the government agreed to provide limited funding for research on the sixth stem cell line created prior to Bush taking office. In 2001 Bush believed that destroying embryos is immoral but since the lines had already been created before he took office he found no reason to curtail the research and using federal money for that would be alright. However, using federal funds to create new human embryos was out of the question and the federal government position on funding embryonic stem cell research has now changed for the better in the protection of the human

Answer 6 question about Japanese Economy Essay Example | Topics and Well Written Essays - 750 words

Answer 6 question about Japanese Economy - Essay Example On the contrary, the American society has yet not adopted anime as a popular medium of advertisement, and advertisements made in America ensure they are not used in advertisements. A2. In the current era, Japan is known for its holistic views regarding product development. The Japanese way of product development consists of six items that makes it different from other economies. These six items include the factor of built in stability, self-organization of project teams, the concept of multi learning, management of subtle control, fostering a culture of organizational transfer of learning, and finally overlapping development phases. A4. One thing everyone knows of who has been to Japan is the high use of vending machines. There are many reasons for the abundance of vending machines within Japan; however, for the purpose of this essay we will shed light at a few important ones. To start off Japan is cash based economy, and unlike other countries cash based transactions are a norm in Japan. This makes buying from vending machines much easier and comfortable for people rather than having to particularly buy from a store which charges cards. Secondly, Japan is a relatively safe country with significantly low crime rates. This makes tampering vending machines less likely, and therefore highlights the possibility of boosting sales through vending machines practically anywhere. Most importantly what needs to be noticed here is that the Japanese people prefer walking long distance rather than taking cars, therefore this helps companies to boost their revenue by placing vending machines at various places so they can be used by passerby’s to purchase things as they walk. A6. Japan is one of the top economies of the world. However, despite this fact the country finds it significantly hard to attract talent across the globe. While there are many reasons for this problem, the bulk of these